A purified fraction of bovine eye lenses has been prepared by a method avoiding detergents and proteolytic enzymes which yielded a dominant junctional membrane component with tetragonal symmetry and a lattice constant of 66 A. The membranes of these junctions were found not to fracture in the usual Brantonian fashion in freeze-fracture-etch (FFE) preparations. Instead the fracture planes ran primarily between the junctional membranes. This lattice was seen as extensive crystalline areas involving the external surfaces of the membranes whether in contact with another membrane or separated by 20-40 nm as they commonly are. The same pattern was seen by negative stain and by x-ray diffraction. A relatively small part of the fraction contained conventional appearing gap junctions as judged from thin sections. The dominant junction appeared very differently from gap junctions in transverse sections being thinner and wavy in character. The proposed research aims at a reexamination of the bovine lens by thin sectioning, FFE, and negative stain electron microscopy. The research aims to localize the tetragonal junction within the intact lens by thin sectioning procedures. In addition purified membrane fractions will be prepared by homogenization of 4 parts of the lens, namely, the anterior epithelial layer, the superficial and deep cortex and the nucleus. The lens has hitherto been regarded as containing only one major junction--the gap junction. The tetragonal lattice has been seen before but regarded as another form of gap junction or of extraneous importance. The present research is aimed at deciding whether or not this is so and elucidating the role of this junction in the lens. The work aims further to do a 3-dimensional image analysis on the square lattice membrane utilizing computer techniques on ice or glucose embedded membranes at 4 degrees K. The studies will be extended from bovine lens to normal and Nakano mouse lenses and human brunescent cataract lenses. The work is considered significant in understanding the mechanism of cataract formation as well as of more general interest in terms of the definition of gap junctions.